Cylinder block structures are well known in the art. Generally, a cylinder block contains numerous internal passages that are oriented in directions directions. Among these internal passages are oil drain passages that individually extend from an upper valley of the cylinder block to the oil pan. It follows that a mold used to cast the cylinder block should comprise a plurality of cores which form these oil drain passages.
However, a problem frequently encountered in the art involves the undesirable shifting of these passage cores upon the addition of molten metal during the casting process. As a result, the cylinder block produced has drain passages that deviate from the original design and undercuts the performance of the engine, e.g. Noise, Vibration, and Harshness (NVH) levels, and structural rigidity of the cylinder block.